CN111734767B - Air spring vibration isolator based on electromagnetic negative stiffness structure - Google Patents
Air spring vibration isolator based on electromagnetic negative stiffness structure Download PDFInfo
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- CN111734767B CN111734767B CN202010605223.6A CN202010605223A CN111734767B CN 111734767 B CN111734767 B CN 111734767B CN 202010605223 A CN202010605223 A CN 202010605223A CN 111734767 B CN111734767 B CN 111734767B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F13/00—Units comprising springs of the non-fluid type as well as vibration-dampers, shock-absorbers, or fluid springs
- F16F13/002—Units comprising springs of the non-fluid type as well as vibration-dampers, shock-absorbers, or fluid springs comprising at least one fluid spring
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F6/00—Magnetic springs; Fluid magnetic springs, i.e. magnetic spring combined with a fluid
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/02—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium using gas only or vacuum
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
- F16F9/32—Details
- F16F9/34—Special valve constructions; Shape or construction of throttling passages
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2222/00—Special physical effects, e.g. nature of damping effects
- F16F2222/12—Fluid damping
- F16F2222/126—Fluid damping using gases
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
- F16F2228/00—Functional characteristics, e.g. variability, frequency-dependence
- F16F2228/06—Stiffness
- F16F2228/063—Negative stiffness
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- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Vibration Prevention Devices (AREA)
Abstract
The air spring vibration isolator based on the electromagnetic negative stiffness structure belongs to the technical field of precise vibration isolation and comprises a double-chamber air spring vibration isolator and an electromagnetic negative stiffness structure, wherein the electromagnetic negative stiffness structure is coaxially nested in a main air chamber of the double-chamber air spring vibration isolator, an annular rubber pad is arranged at the bottom of the main air chamber, and 2-10 throttling holes are uniformly formed between the main air chamber and an additional air chamber; the electromagnetic negative stiffness structure is formed by coaxially nesting an inner fixed magnetic ring, an upper movable magnetic ring, a lower movable magnetic ring and an outer fixed magnetic ring which are symmetrically arranged about the axial height center of the inner fixed magnetic ring, wherein the upper movable magnetic ring and the lower movable magnetic ring are magnetized in opposite directions along the axial direction, and the axial height centers of the inner fixed magnetic ring and the outer fixed magnetic ring are on the same horizontal line and are magnetized in opposite directions along the radial direction; the invention has low natural frequency, large damping coefficient and high integration level and stability.
Description
Technical Field
The invention belongs to the technical field of precise vibration reduction, and particularly relates to an air spring vibration isolator based on an electromagnetic negative stiffness structure.
Background
In the processes of adjustment, test and experiment of precision instruments and equipment, low-frequency micro-amplitude vibration interference in the environment becomes one of key problems influencing the research effect, and the equipping of a large-load-bearing air spring vibration isolator for the precision instruments and equipment gradually becomes a main technical means for inhibiting environmental micro-vibration in the field of large-scale ultra-precision engineering, but the following problems still exist in the research of the air spring vibration isolator:
(1) the natural frequency of the air spring vibration isolator is high, and the low-frequency/ultralow-frequency vibration interference in the environment cannot be inhibited. The existing air spring vibration isolator can achieve large bearing and medium-high frequency vibration suppression effects, but the volume of a cavity needs to be increased for achieving low-frequency/ultralow-frequency vibration suppression, so that the manufacturing cost and the using space are increased, and the low-frequency vibration suppression effect is less obvious along with the increase of the volume of the cavity, so that the air spring vibration isolator is difficult to isolate vibration below 1Hz in actual use.
(2) The system damping of the air spring vibration isolator is small, so that the stable adjustment time under the impact disturbance is long, and the resonance peak value is high. The air spring vibration isolator is a non-contact spring which is characterized in that compressed gas is filled into an elastic membrane, elastic support is realized by utilizing the compressibility of the gas, mechanical friction does not exist, the structural damping of the elastic membrane is used as a main damping source of the air spring vibration isolator, the damping coefficient is small, so that the vibration energy attenuation is slow under the excitation of impact disturbance, the system stability adjustment time is long, and the resonance peak value is high.
(3) The air spring vibration isolator with the parallel magnetic negative stiffness structure has low integration level and poor stability and is influenced by the floating height of the positive stiffness supporting element. The magnetic negative stiffness structure is connected with the air spring vibration isolator in parallel, so that the inherent frequency can be reduced under the condition of ensuring the large bearing of the air spring vibration isolator, and the low-frequency/ultralow-frequency vibration isolation effect with large bearing is realized. However, the existing low-frequency vibration isolator formed by connecting the cubic permanent magnet negative stiffness structure and the air spring vibration isolator in parallel has large volume and low system integration level, and the stiffness value of the negative stiffness structure is influenced by the floating height of the air spring vibration isolator; for the air spring vibration isolator with the nested coaxial magnetic ring negative stiffness structure, the coaxial magnetic ring negative stiffness structure is arrayed along the axial direction, so that the gravity center height of the vibration isolator can be improved in a mode of increasing the negative stiffness value, and the stability of the vibration isolator is reduced.
(4) The air spring vibration isolator with the parallel magnetic negative stiffness structure has no corresponding protection measure on impact disturbance excitation. The large-amplitude impact disturbance excitation causes rigid collision between the moving magnet and the fixed magnet or between the moving magnet and the fixed magnet fixing piece of the magnetic negative rigidity structure, and the magnet is easy to damage or break.
Patent No. CN201310142491.9 discloses a positive and negative stiffness parallel damper. According to the technical scheme, the magnetic negative stiffness structure is coaxially arranged in the air spring vibration isolator cavity to form the positive and negative stiffness parallel connection vibration absorber, the magnetic negative stiffness structure is formed by two coaxial magnetic rings magnetized reversely along the radial direction, the structure is compact, and the influence of the floating height of the air spring vibration isolator on the stiffness value of the magnetic negative stiffness structure is not required to be considered. The technical scheme is characterized in that: 1) the magnetic negative stiffness structure axial array leads the positive and negative stiffness parallel shock absorber to have high gravity center and poor stability in a mode of increasing the negative stiffness value; 2) the magnetic negative stiffness structure is in a non-contact action mode, and the damping characteristic of the air spring vibration isolator is not improved; 3) under the excitation of impact disturbance, the magnetic negative stiffness structure has no corresponding protective measures.
Patent numbers CN201610914596.5 and CN201610914512.8 disclose a magnetic negative stiffness structure to reduce the natural frequency of the air spring vibration isolator, the magnetic negative stiffness structure is composed of three cubic permanent magnets with the same magnetization direction and arranged along a vertical equal gap array, and the stiffness value can be adjusted by changing the gap of the permanent magnets. The technical scheme is characterized in that: 1) the large floating height can increase the gap of the permanent magnet for the large-load air spring vibration isolator, so that the rigidity value of the magnetic negative rigidity structure is very small, and the effect of reducing the natural frequency of the air spring vibration isolator is not obvious; 2) the structural damping of the elastic membrane is small; 3) the air spring vibration isolator and the magnetic negative stiffness structure are arranged in a split manner, so that the system integration level is low and the volume is large; 4) under the excitation of impact disturbance, the magnetic negative stiffness structure has no corresponding protective measures.
Patent No. CN201810853079.0 discloses a quasi-zero stiffness vibration isolator with parallel positive and negative stiffness. According to the technical scheme, the magnetic negative stiffness structure is formed by the coaxial double magnetic rings magnetized in the axial direction, and the magnetic rings are convenient to axially magnetize and process; the magnetic ring gap is vertical to the rising and falling movement direction of the positive rigidity supporting element, so that the influence of the floating height of the positive rigidity supporting element on the rigidity value of the magnetic negative rigidity structure is not required to be considered. The technical scheme is characterized in that: 1) the magnetic negative stiffness structure is in a non-contact action mode, and the damping characteristic of the air spring vibration isolator is not improved; 2) the magnetic negative stiffness structure increases the negative stiffness value and reduces the stiffness value of the positive stiffness supporting element in an axial array mode, and the axial array mode causes high gravity center and poor stability of the vibration isolator; 3) the magnetic negative stiffness structures are uniformly distributed on the left side and the right side of the positive stiffness supporting element, and the system is low in integration level and large in size.
In conclusion, through the innovation of the vibration isolation structure and the principle, the magnetic negative stiffness structure which has high integration degree, high stability and large damping and is not influenced by the floating height of the positive stiffness supporting element is provided to offset the positive stiffness value of the large-bearing air spring vibration isolator, so that the magnetic negative stiffness structure has great significance for further improving the low-frequency vibration isolation performance of the micro-vibration isolation platform, increasing the structural damping and quickly attenuating the vibration energy.
Disclosure of Invention
The invention aims to solve the problems that the natural frequency of a large-bearing air spring vibration isolator cannot meet the low-frequency/ultralow-frequency vibration isolation requirement of precision instruments and equipment, the stable adjustment time under impact disturbance is long due to a small damping coefficient, the resonance peak value is high, and an electromagnetic negative stiffness structure does not have corresponding protection measures under the excitation of the impact disturbance, and provides an air spring vibration isolator based on an electromagnetic negative stiffness structure.
The technical solution of the invention is as follows:
an air spring vibration isolator based on an electromagnetic negative stiffness structure comprises an air spring vibration isolator and an electromagnetic negative stiffness structure, wherein the electromagnetic negative stiffness structure is coaxially nested in the air spring vibration isolator, the whole structure is in axial symmetry, the air spring vibration isolator comprises a main air chamber, an elastic membrane, an inner compression ring and an outer compression ring, the outer end of the annular elastic membrane is tightly pressed and fixed on the main air chamber by the outer compression ring, and the top end of the inner compression ring supports a vibration isolation load; the air spring vibration isolator further comprises an additional air chamber, the additional air chamber is fixedly installed right below the main air chamber, an air inlet is formed in the side wall of the additional air chamber, 2-10 throttling holes are uniformly formed between the main air chamber and the additional air chamber, the main air chamber is made of aluminum alloy, titanium alloy and austenitic stainless steel which are not or weakly magnetic, and an annular rubber pad is arranged at the bottom of the main air chamber; the electromagnetic negative stiffness structure comprises a fixed magnetic ring fixing piece, an inner fixed magnetic ring, a moving magnetic ring mounting piece, a moving magnetic ring and an outer fixed magnetic ring which are coaxially nested outwards along the radius of the axis, the fixed magnetic ring fixing piece and the moving magnetic ring mounting piece are made of non-magnetic or weakly magnetic aluminum alloy, titanium alloy or austenitic stainless steel, the inner fixed magnetic ring is fixedly arranged on the outer wall of the fixed magnetic ring fixing piece, the bottom of the fixed magnetic ring fixing piece is fixedly connected with the bottom of the main air chamber, a gap is arranged between the inner fixed magnetic ring and the moving magnetic ring mounting piece along the radial direction, the moving magnetic ring comprises an upper moving magnetic ring and a lower moving magnetic ring, the upper moving magnetic ring and the lower moving magnetic ring are arranged symmetrically relative to the axial height center of the fixed magnetic ring, the upper moving magnetic ring and the lower moving magnetic ring are magnetized reversely along the axial direction and are fixedly connected to the outer wall of the moving magnetic ring mounting piece, the inner pressure ring presses and fixes the inner end of the annular elastic film on the top end of the moving magnetic ring mounting piece, and the moving and outer fixed magnetic ring are provided with a gap along the radial direction, the outer fixed magnetic ring is fixedly arranged on the inner wall of the main air chamber, the axial height centers of the inner fixed magnetic ring and the outer fixed magnetic ring are on the same horizontal line and are oppositely magnetized along the radial direction, the inner fixed magnetic ring and the upper movable magnetic ring have a repulsive force effect, the inner fixed magnetic ring and the lower movable magnetic ring have a repulsive force effect, the outer fixed magnetic ring and the upper movable magnetic ring have a repulsive force effect, and the outer fixed magnetic ring and the lower movable magnetic ring have a repulsive force effect.
Preferably, the inner fixed magnetic ring is magnetized outwards along a radius from the axis and the upper moving magnetic ring is magnetized downwards along the axial direction, or the inner fixed magnetic ring is magnetized towards the axis along the radius and the upper moving magnetic ring is magnetized upwards along the axial direction.
Preferably, the inner fixed magnetic ring, the outer fixed magnetic ring, the upper moving magnetic ring and the lower moving magnetic ring are permanent magnets or electromagnets.
Preferably, the orifice is circular, elliptical, or polygonal in shape.
Preferably, the diameter of the circumcircle of the throttle hole is 1 mm-10 mm.
Preferably, the volume of the additional air chamber is no more than 3 times the volume of the main air chamber.
Preferably, the elastic membrane is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
Preferably, the rubber pad is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
The technical innovation and the good effect of the invention are as follows:
(1) the technical scheme realizes the large bearing and near-zero frequency vibration isolation effects of the air spring vibration isolator and has the characteristic of high integration level. According to the invention, on one hand, the rigidity value and the inherent frequency of the air spring vibration isolator are reduced by serially connecting the additional air chambers, on the other hand, the near-zero frequency vibration isolation effect under the condition of large bearing is realized by coaxially nesting the electromagnetic negative rigidity structure in the main air chamber of the air spring vibration isolator, the full-frequency-band micro-vibration interference in the environment where the ultra-precise instrument and equipment is located is effectively isolated, and meanwhile, the integration level of the system is improved. This is one of the innovative points of the present invention from the prior art.
(2) The throttling hole damping and the eddy current damping generated by the invention can effectively accelerate the vibration energy attenuation and shorten the system stabilization time. Orifices with different shapes, sizes and numbers are arranged between the main air chamber and the additional air chamber so as to introduce orifice damping and increase system damping; in addition, under disturbance excitation, eddy current damping generated in the main air chamber and the fixed magnetic ring fixing frame can effectively restrain the motion of the brake magnetic ring relative to the fixed magnetic ring, quickly attenuate vibration energy and shorten the system stabilization time. This is the second innovation point of the present invention from the prior art.
(3) According to the technical scheme, the electromagnetic negative stiffness structure is formed by coaxially nesting the perpendicularly magnetized magnetic rings, so that the influence of the floating height of the air spring vibration isolator on the negative stiffness value can be avoided, and the high stability characteristic is realized. The radial magnetized fixed magnetic ring and the axial magnetized movable magnetic ring are coaxially nested to form an electromagnetic negative stiffness structure, the gap of the magnetic rings is vertical to the rising and falling movement direction of the air spring vibration isolator, and the influence of the floating height of the air spring vibration isolator on the stiffness value of the electromagnetic negative stiffness structure is eliminated; the mode of increasing the negative rigidity value of the radial array magnetic ring can effectively avoid the problems of gravity center height lifting and stability reduction of the electromagnetic negative rigidity structure caused by the axial array mode of the magnetic ring. This is the third innovation point of the present invention from the prior art.
(4) The invention can effectively avoid rigid collision under the excitation of impact disturbance. According to the invention, the rubber pad is arranged at the bottom of the main air chamber of the air spring vibration isolator as a protection measure of an electromagnetic negative stiffness structure, so that the phenomenon that the moving magnetic ring is rigidly collided with the bottom of the main air chamber under the excitation of impact disturbance to cause damage to the magnetic ring can be effectively avoided. This is the fourth innovation point of the present invention from the prior art.
Drawings
FIG. 1 is a schematic three-dimensional cross-sectional view of an air spring vibration isolator based on an electromagnetic negative stiffness structure;
FIG. 2 is a schematic cross-sectional front view of an air spring vibration isolator based on an electromagnetic negative stiffness structure;
FIG. 3 is a schematic view of the magnetization direction of a magnetic ring in an electromagnetic negative stiffness structure;
FIG. 4 is a force analysis diagram at an equilibrium position of an electromagnetic negative stiffness structure;
FIG. 5 is a force analysis diagram of the electromagnetic negative stiffness structure moving upward away from equilibrium;
FIG. 6 is a force analysis diagram of the electromagnetic negative stiffness structure moving downward away from equilibrium;
FIG. 7 is an embodiment of the shape of the circular orifice at the top of the additional air chamber;
FIG. 8 is another embodiment of an elliptical orifice shape at the top end of the additional chamber;
FIG. 9 is another embodiment of the square orifice shape at the top of the additional air chamber.
Description of part numbers in the figures: 1 air inlet, 2 rubber pads, 3 main air chambers, 4 additional air chambers, 5 elastic films, 6 internal pressure rings, 7 external pressure rings, 8a internal fixed magnetic ring, 8b external fixed magnetic ring, 9 fixed magnetic ring fixing pieces, 10 movable magnetic rings, 10a upper movable magnetic ring, 10b lower movable magnetic ring, 11 movable magnetic ring mounting pieces and 12 throttling holes.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings.
An air spring vibration isolator based on an electromagnetic negative stiffness structure comprises the air spring vibration isolator and the electromagnetic negative stiffness structure, wherein the electromagnetic negative stiffness structure is coaxially nested in the air spring vibration isolator, the whole structure is in axial symmetry, the air spring vibration isolator comprises a main air chamber 3, an elastic membrane 5, an inner compression ring 6 and an outer compression ring 7, the outer compression ring 7 compresses and fixes the outer end of the annular elastic membrane 5 on the main air chamber 3, and the top end of the inner compression ring 6 supports a vibration isolation load; the air spring vibration isolator further comprises an additional air chamber 4, the additional air chamber 4 is fixedly installed right below the main air chamber 3, an air inlet 13 is formed in the side wall of the additional air chamber 4, 2-10 throttling holes 12 are uniformly formed between the main air chamber 3 and the additional air chamber 4, the main air chamber 3 is made of non-magnetic or weak-magnetic aluminum alloy, titanium alloy and austenitic stainless steel, and an annular rubber pad 14 is arranged at the bottom of the main air chamber 3; the electromagnetic negative stiffness structure comprises a fixed magnetic ring fixing piece 9, an inner fixed magnetic ring 8a, a moving magnetic ring mounting piece 11, a moving magnetic ring 10 and an outer fixed magnetic ring 8b which are coaxially nested outwards along the radius of the axis, the fixed magnetic ring fixing piece 9 and the moving magnetic ring mounting piece 11 are made of non-magnetic or weakly magnetic aluminum alloy, titanium alloy or austenitic stainless steel, the inner fixed magnetic ring 8a is fixedly arranged on the outer wall of the fixed magnetic ring fixing piece 9, the bottom of the fixed magnetic ring fixing piece 9 is fixedly connected with the bottom of the main air chamber 3, a gap is arranged between the inner fixed magnetic ring 8a and the moving magnetic ring mounting piece 11 along the radial direction, the moving magnetic ring 10 comprises an upper moving magnetic ring 10a and a lower moving magnetic ring 10b, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are symmetrically arranged relative to the axial height center of the fixed magnetic ring 8, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are magnetized in the axial direction and fixedly connected to the outer wall of the moving mounting piece 11, the inner end of the annular elastic film 5 is pressed and fixed on the top end of the moving magnetic ring mounting piece 11 by the inner end of the inner fixed magnetic ring 6, a gap is arranged between the movable magnetic ring 10 and the outer fixed magnetic ring 8b along the radial direction, the outer fixed magnetic ring 8b is fixedly arranged on the inner wall of the main air chamber 3, the axial height centers of the inner fixed magnetic ring 8a and the outer fixed magnetic ring 8b are on the same horizontal line and are magnetized reversely along the radial direction, the inner fixed magnetic ring 8a and the upper movable magnetic ring 10a are in a repulsion action, the inner fixed magnetic ring 8a and the lower movable magnetic ring 10b are in a repulsion action, the outer fixed magnetic ring 8b and the upper movable magnetic ring 10a are in a repulsion action, and the outer fixed magnetic ring 8b and the lower movable magnetic ring 10b are in a repulsion action.
In a specific embodiment, the inner fixed magnetic ring 8a is magnetized radially outward from the axis, the upper moving magnetic ring 10a is magnetized axially downward or the inner fixed magnetic ring 8a is magnetized radially toward the axis, and the upper moving magnetic ring 10a is magnetized axially upward.
As a specific implementation manner, the inner fixed magnetic ring 8a, the outer fixed magnetic ring 8b, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are permanent magnets or electromagnets.
In a specific embodiment, the orifice 12 has a circular, elliptical, or polygonal shape.
In a specific embodiment, the diameter of the circumcircle of the orifice 12 is 1mm to 10 mm.
In a particular embodiment, the volume of the additional air chamber 4 is not greater than 3 times the volume of the main air chamber 3.
In a specific embodiment, the elastic membrane 5 is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
In a specific embodiment, the rubber pad 14 is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
An embodiment of the present invention is given below with reference to fig. 1 to 3.
Fig. 1 and fig. 2 are a schematic three-dimensional cross-sectional view and a schematic positive cross-sectional view of the positive and negative stiffness parallel vibration isolator provided by the invention, respectively, and fig. 3 is a schematic magnetization direction of a magnetic ring in an electromagnetic negative stiffness structure. As shown in fig. 1 and 2, the air spring vibration isolator based on the electromagnetic negative stiffness structure provided by the invention comprises an air spring vibration isolator and an electromagnetic negative stiffness structure, wherein the air spring vibration isolator and the electromagnetic negative stiffness structure are coaxially installed and are arranged in parallel, and the whole air spring vibration isolator is axisymmetric. The air spring vibration isolator comprises a main air chamber 3, an additional air chamber 4, an elastic membrane 5, an internal compression ring 6 and an external compression ring 7, wherein the main air chamber 3 and the additional air chamber 4 are made of 304 stainless steel materials, the volume of the additional air chamber 4 is 3 times of that of the main air chamber 3, the positive stiffness generated by the air spring vibration isolator is reduced by 75%, the inherent frequency is reduced by 50%, and the bearing capacity of the air spring vibration isolator is not changed. Elastic membrane 5 is the loop configuration with outer clamping ring 7, and interior clamping ring 6 is cylindrical structure, and elastic membrane 5 is vulcanized by rubber and nylon cord and forms, and the material of interior clamping ring 6 and outer clamping ring 7 is light aluminum alloy. The top end of the inner compression ring 6 supports vibration isolation load, the bottom of the inner compression ring 6 compresses and fixes the inner end of the elastic membrane 5 to the top end of the movable magnetic ring mounting part 11, and the outer compression ring 7 compresses and fixes the outer end of the elastic membrane 5 to the side wall of the main air chamber 3. The rubber pad 2 which is 2mm thick and is formed by vulcanizing rubber and nylon cords is arranged at the bottom of the main air chamber 3 and is used for preventing the movable magnetic ring 10 of the negative-stiffness magnetic spring 1 from colliding with the main air chamber 3 due to large vibration displacement. The bottom of the main air chamber 3 and the top end of the chamber of the additional air chamber 4 are uniformly provided with 6 round holes with the diameter of phi 5mm along the circumference with the diameter of 40mm, the top end of the additional air chamber 4 is provided with a round hole with the diameter equal to the outer diameter of the chamber of the main air chamber 3, the depth is a round groove with the diameter of 1mm, the main air chamber 3 is coaxially and fixedly arranged in the round groove on the top end of the chamber of the additional air chamber 4, the bottom of the main air chamber 3 is opposite to the round hole on the top end of the chamber of the additional air chamber 4, and the main air chamber is used as a throttling hole 12 of the double-chamber air spring vibration isolator, and is used for increasing the damping of a system and reducing the resonance peak value and shortening the stabilization time. The side wall of the additional air chamber 4 is provided with a circular air inlet 1, clean compressed air is introduced into the air inlet 1 through an air supply system to support vibration isolation load, the working air pressure of the air spring vibration isolator is 0.3MPa, and the floating height is 10 mm.
The negative-stiffness magnetic spring comprises a fixed magnetic ring fixing piece 9, an inner fixed magnetic ring 8a, a moving magnetic ring mounting piece 11, a moving magnetic ring 10 and an outer fixed magnetic ring 8b, the fixed magnetic ring fixing piece 9 and the moving magnetic ring mounting piece 11 are made of 304 stainless steel, the moving magnetic ring 10 comprises an upper moving magnetic ring 10a and a lower moving magnetic ring 10b, the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are symmetrically mounted relative to the axial height center of the inner fixed magnetic ring 8a, and the axial height centers of the inner fixed magnetic ring 8a and the outer fixed magnetic ring 8b are equal in height. The inner fixed magnetic ring 8a is magnetized outwards along the radius from the axis, the upper moving magnetic ring 10a is magnetized downwards along the axial direction, the lower moving magnetic ring 10b is magnetized upwards along the axial direction, the inner fixed magnetic ring 8a is magnetized along the radius to the axis, and the magnetization direction of the magnetic rings is shown as the arrow in figure 3; the inner fixed magnetic ring 8a is fixedly arranged on the outer wall of the fixed magnetic ring fixing piece 9, the bottom of the fixed magnetic ring fixing piece 9 is fixedly connected with the bottom of the main air chamber 3, a gap is arranged between the inner fixed magnetic ring 8a and the movable magnetic ring mounting piece 11 along the radial direction, the upper movable magnetic ring 10a and the lower movable magnetic ring 10b are fixedly connected on the outer wall of the movable magnetic ring mounting piece 11, the inner diameters of the upper movable magnetic ring 10a and the lower movable magnetic ring 10b are equal to the outer diameter of the movable magnetic ring mounting piece 11, the upper movable magnetic ring 10a and the lower movable magnetic ring 10b are coaxially nested and fixedly arranged on the outer wall of the movable magnetic ring mounting piece 11, the bottom of the upper movable magnetic ring 10a is connected with the top end of the lower movable magnetic ring 10b, the bottom of the upper movable magnetic ring 10a is 10mm lower than the axial height center of the inner fixed magnetic ring 8a and the outer fixed magnetic ring 8b, the magnetic ring is made of N50 brand neodymium iron boron, the residual magnetic induction intensity is 1.43T, and the relative magnetic conductivity is 1.03. When the air spring vibration isolator is inflated to 0.3MPa, the elastic membrane 5 expands under the action of compressed air, the inner compression ring 6 drives the upper moving magnetic ring 10a and the lower moving magnetic ring 10b to move upwards for 10mm along the axial direction through the moving magnetic ring mounting piece 11, so that the axial height centers of the inner fixed magnetic ring 8a and the outer fixed magnetic ring 8b are equal to the bottom of the upper moving magnetic ring 10a and the top of the lower moving magnetic ring 10b in height, the inner compression ring 6 compresses the inner end of the annular elastic membrane 5 and fixes the inner end of the moving magnetic ring mounting piece 11 at the top end of the moving magnetic ring mounting piece 11, a gap is arranged between the moving magnetic ring 10 and the outer fixed magnetic ring 8b along the radial direction, the outer diameter of the outer fixed magnetic ring 8b is equal to the inner diameter of the main air chamber 3, and the gap is fixedly installed on the inner wall of the main air chamber 3. Under the interference of external vibration, the upper movable magnetic ring 10a and the lower movable magnetic ring 10b move relative to the inner fixed magnetic ring 8a and the outer fixed magnetic ring 8b, magnetic induction lines generated by the upper movable magnetic ring 10a and the lower movable magnetic ring 10b cut the main air chamber 3 and the fixed magnetic ring fixing piece 9, so that electric eddy currents are generated in the main air chamber 3 and the fixed magnetic ring fixing piece 9, eddy current damping hinders the upper movable magnetic ring 10a and the lower movable magnetic ring 10b from moving relative to the inner fixed magnetic ring 8a and the outer fixed magnetic ring 8b, vibration attenuation is accelerated, and the stable adjustment time of the vibration isolation system is shortened.
FIG. 4 is a force analysis diagram of the balanced position of the electromagnetic negative stiffness structure, in which the upper moving magnetic ring 10a and the lower moving magnetic ring 10b are located in the magnetic field excited by the inner fixed magnetic ring 8a and the outer fixed magnetic ring 8b, and the magnetic force applied to the electromagnetic negative stiffness structure is the repulsive force f of the upper moving magnetic ring 10a and the lower moving magnetic ring 10b from the outer fixed magnetic ring 8b1、f2The upper moving magnetic ring 10a and the lower moving magnetic ring 10b are subjected to the repulsion force f of the inner fixed magnetic ring 8a3、f4And (4) summing. At the balance position, the bottom of the upper moving magnetic ring 10a, the top of the lower moving magnetic ring 10b and the axial height center of the fixed magnetic ring 8 are on the same horizontal line, and the magnetic force f1、f2、f3、f4The fixed magnetic ring points to the moving magnetic ring along the horizontal direction, and the magnetic force borne by the electromagnetic negative stiffness structure at the balance position is 0 due to the symmetry of the electromagnetic negative stiffness structure.
FIG. 5 is a force analysis diagram of the electromagnetic negative stiffness structure moving upward away from the equilibrium position, where the bottom of the upper moving magnetic ring 10a is connected to the top of the lower moving magnetic ring 10b and is higher than the axial height center of the stationary magnetic ring 8, and f1Pointing to the axis along the central connecting line of the outer fixed magnetic ring 8b and the upper moving magnetic ring 10a, f2Pointing to the axis along the central connecting line of the outer fixed magnetic ring 8b and the lower movable magnetic ring 10b, f3Pointing to the axis along the central connecting line of the inner fixed magnetic ring 8a and the upper moving magnetic ring 10a, f4Pointing to the axis along the central connecting line of the inner fixed magnetic ring 8a and the lower moving magnetic ring 10b, f due to the symmetry of the electromagnetic negative stiffness structure1、f2、f3、f4Diameter ofThe directional component forces are mutually offset, and the axial component forces which are mutually superposed force the electromagnetic negative stiffness structure to deviate from the balance position and move upwards along the axis.
FIG. 6 is a force analysis diagram of the electromagnetic negative stiffness structure moving downward from the equilibrium position, where the bottom of the upper moving magnetic ring 10a is connected to the top of the lower moving magnetic ring 10b and is lower than the axial height center of the stationary magnetic ring 8, and f1A central connecting line between the outer fixed magnetic ring 8b and the upper moving magnetic ring 10a is far away from the axis, f2A central connecting line along the outer fixed magnetic ring 8b and the lower movable magnetic ring 10b is far away from the axis, f3F is far away from the axis along the central connecting line of the inner fixed magnetic ring 8a and the upper moving magnetic ring 10a4The central connecting line of the inner fixed magnetic ring 8a and the lower moving magnetic ring 10b is far away from the axis, f is the symmetry of the electromagnetic negative stiffness structure1、f2、f3、f4The radial component forces are mutually offset, and the axial component forces which are mutually superposed force the electromagnetic negative stiffness structure to deviate from the balance position and move downwards along the axis.
Fig. 7 to 9 show three embodiments of the shape of the orifice at the top end of the additional air chamber 4. 6 circular throttling holes are uniformly distributed at the top end of the additional air chamber 4 along the circumference in fig. 7, 6 oval throttling holes are uniformly distributed at the top end of the additional air chamber 4 along the circumference in fig. 8, and 6 square throttling holes are uniformly distributed at the top end of the additional air chamber 4 along the circumference in fig. 9.
Claims (8)
1. An air spring vibration isolator based on an electromagnetic negative stiffness structure comprises the air spring vibration isolator and the electromagnetic negative stiffness structure, wherein the electromagnetic negative stiffness structure is coaxially nested in the air spring vibration isolator, the whole structure is in axial symmetry, the air spring vibration isolator comprises a main air chamber (3), an elastic membrane (5), an inner compression ring (6) and an outer compression ring (7), the outer end of the annular elastic membrane (5) is pressed and fixed on the main air chamber (3) by the outer compression ring (7), and the top end of the inner compression ring (6) supports a vibration isolation load; the method is characterized in that: the air spring vibration isolator further comprises an additional air chamber (4), the additional air chamber (4) is fixedly installed right below the main air chamber (3), an air inlet hole (13) is formed in the side wall of the additional air chamber (4), 2-10 throttling holes (12) are uniformly formed between the main air chamber (3) and the additional air chamber (4), the main air chamber (3) is made of non-magnetic or weak-magnetic aluminum alloy, titanium alloy and austenitic stainless steel, and an annular rubber pad (14) is arranged at the bottom of the main air chamber (3); the electromagnetic negative stiffness structure comprises a fixed magnetic ring fixing piece (9), an inner fixed magnetic ring (8a), a moving magnetic ring mounting piece (11), a moving magnetic ring (10) and an outer fixed magnetic ring (8b) which are coaxially nested outwards along a radius from an axis, the fixed magnetic ring fixing piece (9) and the moving magnetic ring mounting piece (11) are made of non-magnetic or weakly magnetic aluminum alloy, titanium alloy or austenitic stainless steel, the inner fixed magnetic ring (8a) is fixedly arranged on the outer wall of the fixed magnetic ring fixing piece (9), the bottom of the fixed magnetic ring fixing piece (9) is fixedly connected with the bottom of the main air chamber (3), a gap is arranged between the inner fixed magnetic ring (8a) and the moving magnetic ring mounting piece (11) along the radial direction, the moving magnetic ring (10) comprises an upper moving magnetic ring (10a) and a lower moving magnetic ring (10b), and the upper moving magnetic ring (10a) and the lower moving magnetic ring (10b) are symmetrically arranged relative to the axial height center of the fixed magnetic ring (8), the upper movable magnetic ring (10a) and the lower movable magnetic ring (10b) are magnetized reversely along the axial direction and are fixedly connected with the outer wall of the movable magnetic ring mounting piece (11), the inner end of the annular elastic film (5) is pressed and fixed at the top end of the movable magnetic ring mounting piece (11) by the inner pressure ring (6), a gap is arranged between the movable magnetic ring (10) and the outer fixed magnetic ring (8b) along the radial direction, the outer fixed magnetic ring (8b) is fixedly arranged on the inner wall of the main air chamber (3), the axial height centers of the inner fixed magnetic ring (8a) and the outer fixed magnetic ring (8b) are on the same horizontal line, and the magnetization is carried out along the radial direction in an opposite direction, the inner fixed magnetic ring (8a) and the upper moving magnetic ring (10a) have a repulsion function, the inner fixed magnetic ring (8a) and the lower moving magnetic ring (10b) have a repulsion function, the outer fixed magnetic ring (8b) and the upper moving magnetic ring (10a) have a repulsion function, and the outer fixed magnetic ring (8b) and the lower moving magnetic ring (10b) have a repulsion function.
2. The air spring vibration isolator based on electromagnetic negative stiffness structure according to claim 1, characterized in that: the inner fixed magnetic ring (8a) is magnetized outwards along the radius from the axis, the upper movable magnetic ring (10a) is magnetized downwards along the axial direction, or the inner fixed magnetic ring (8a) is magnetized along the radius to the axis, and the upper movable magnetic ring (10a) is magnetized upwards along the axial direction.
3. The air spring vibration isolator based on electromagnetic negative stiffness structure according to claim 1, characterized in that: the inner fixed magnetic ring (8a), the outer fixed magnetic ring (8b), the upper moving magnetic ring (10a) and the lower moving magnetic ring (10b) are permanent magnets or electromagnets.
4. The air spring vibration isolator based on electromagnetic negative stiffness structure according to claim 1, characterized in that: the orifice (12) is circular, elliptical or polygonal in shape.
5. The air spring vibration isolator based on electromagnetic negative stiffness structure according to claim 1, characterized in that: the diameter of the circumcircle of the throttle hole (12) is 1 mm-10 mm.
6. The air spring vibration isolator based on electromagnetic negative stiffness structure according to claim 1, characterized in that: the volume of the additional air chamber (4) is not more than 3 times of the volume of the main air chamber (3).
7. The air spring vibration isolator based on electromagnetic negative stiffness structure according to claim 1, characterized in that: the elastic membrane (5) is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
8. The air spring vibration isolator based on electromagnetic negative stiffness structure according to claim 1, characterized in that: the rubber pad (14) is formed by vulcanizing a rubber material and a nylon cord or a polyester cord.
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| CN114658783A (en) * | 2022-03-22 | 2022-06-24 | 中国人民解放军海军工程大学 | Quasi-zero stiffness vibration isolator with adjustable positive and negative stiffness |
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| CN101709763B (en) * | 2009-12-10 | 2012-07-04 | 华中科技大学 | Horizontal two-degree-of-freedom vibration isolating mechanism |
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| CN104315068A (en) * | 2014-08-28 | 2015-01-28 | 哈尔滨恒信防微振技术开发有限公司 | Low-frequency air spring vibration isolator with motion converter |
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